Copper/Tungsten　(Cu/W)　nano-multilayers　show　potential　for　application　as　novel　low-temperature　brazing　filler　metals.　Therefore,　researchers　are　interested　in　understanding　phase　stability　and　microstructural　evolution　of　the　nano-multilayers　during　thermal　treatment.　A　repetition　of　50　alternating　nanolayers　of　Cu　and　W　with　individual　thicknesses　of　10　nm　were　prepared　by　magnetron-sputtering　on　silicon　substrates.　The　structural　evolution　of　Cu/W　nano-multilayers　(NMLs)　within　the　temperature　range　400　&　DEG;C-800　&　DEG;C　was　monitored　using　real-time　in-situ　XRD,　SEM,　TEM,　SAXS,　DSC　and　in-house　XRD　system.　The　results　showed　that　the　melting　point　of　Cu/W　nano-multilayers　determined　using　DSC　was　793.694　&　DEG;C　was　remarkably　lower　than　the　melting　point　of　bulk　Cu(1083　&　DEG;C)　and　W　(3140　&　DEG;C).　After　annealing　at　400　&　DEG;C　for　30　min,　the　surface　of　the　NMLs　exhibited　more　copper　grains,　with　significant　coarsening　of　the　copper　grains.　The　layered　structure　of　the　Cu/W　NMLs　was　unaffected　after　annealed　at　400　&　DEG;C.　When　annealed　at　600　&　DEG;C　for　30　min,　some　Cu　particles　migrated　into　the　W　layers　along　the　internal　interface　leading　to　cracks　which　partially　collapsed　the　original　stratified　structure.　The　nano-multilayered　structure　was　completely　destroyed　when　annealed　at　800　&　DEG;C.　Further,　the　in-situ　XRD　results　showed　that　the　copper　grains　grew　substantially,　while　the　tungsten　size　remained　unchanged　with　increasing　temperature.